Bottom-Up Regulation of Perovskite Growth and Energetics via Oligoether Functionalized Self-Assembling Molecules for High-Performance Solar Cells.

Self-assembling molecules (SAMs) are widely used as interfacial layers to optimize the surface properties of nickel oxides (NiO) in inverted perovskite solar cells (PSCs). However, less attention is paid to the effect of SAMs on the regulation of perovskite growth and energetics. Here, based on the donor-acceptor molecular backbone, an oligoether chain is introduced with different chain lengths to endow two novel SAMs, namely, EPA and MEPA, with good capability of bottom-up regulation of perovskite formation and energetics. Compared to the model SAM MPA, EPA and MEPA can render NiO with better coverage and conductivity. Moreover, the oligoether chain-containing SAMs are able to assist the formation of perovskite film with ordered growth, high crystallization, and importantly well-matched energy level alignment at the top surface, especially for MEPA. Consequently, a remarkably high efficiency of 25.50% is realized for NiO/MEPA-based PSCs along with good device stability, which can maintain 90% of the initial efficiency under ISOS-L-1 conditions over 1260 h.